internal string TestRegex_GenerateInput(SymbolicRegexBuilder <BV> builder, int nrOfMatches, int randomTextSizeLimit, SymbolicRegexNode <BV> sr)
        {
            if (nrOfMatches < 1)
            {
                throw new ArgumentOutOfRangeException();
            }

            string str = sr.GenerateRandomMember();

            for (int i = 1; i < nrOfMatches; i++)
            {
                if (randomTextSizeLimit > 0)
                {
                    int    k   = rnd.Next(0, randomTextSizeLimit);
                    string tmp = sr.GenerateRandomMember();
                    int    j   = rnd.Next(1, tmp.Length);
                    str += tmp.Substring(0, j) + CreateRandomString(k) + tmp.Substring(j);
                }
                str += sr.GenerateRandomMember();
            }
            return(str);
        }